/**
 * @author Derek Hardison <http://cs.roanoke.edu/~dmhardison/><br>
 *         File: WhoisProc.java<br>
 *         Purpose: Performs WHOIS lookup on a domain name and collects
 *         registrar, name server 1, and name server 2.<br>
 *         <br>
 *         This work is licensed under the Creative Commons Attribution-Share
 *         Alike 3.0 License. To view a copy of this license, visit
 *         http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to
 *         Creative Commons, 171 Second Street, Suite 300, San Francisco,
 *         California, 94105, USA.
 */

import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class WhoisProc {
    // ASSERT: WHOISSERVER is a list of WHOIS servers and ports to connect to;
    // if server returns no results the next server will be tried.
    final String WHOISSERVER[][] = { { "internic.net", "43" },
            { "whois.pir.org", "43" } };

    // ASSERT: WHOISPORT is the whois server port to query on.
    final int WHOISTIMEOUT = 20000;

    // ASSERT: WHOISTIMEOUT is the timeout till considered a failed
    // connection to the whois server.

    final String REGISTRARSTRING = "registrar:"; // ALL LOWERCASE

    final String NAMESERVER1STRING = "name server:";

    final String NAMESERVER2STRING = "name server:";

    // ------------- END OF CONFIGURATION ----------------//
    private String hostname;

    // ASSERT: hostname is not set.
    private String registrar;

    // ASSERT: registrar is not set.
    private String ns1;

    // ASSERT: ns1 is not set.
    private String ns2;

    // ASSERT: ns2 is not set.
    protected Socket s;

    // ASSERT: s is not set.

    /**
     * Constructs the object and performs initial domain WHOIS lookup.
     * 
     * @param h
     *        Domain name to perform WHOIS lookup on.
     * @throws Exception
     *         If unable to collect WHOIS information on the domain name (ie
     *         WHOIS information is private or domain does not exist).
     */
    public WhoisProc(String h) throws Exception {
        collectDomainInformation(h);
    }

    /**
     * Peforms WHOIS lookup on domain name using specified WHOIS servers in
     * source file.
     * 
     * @param h
     *        Domain name to perform WHOIS search for.
     * @throws Exception
     *         Throws exception if unable to resolve domain name, or response
     *         from WHOIS server is not valid (No valid information returned on
     *         the domain).
     */
    private void collectDomainInformation(String h) throws Exception {
        hostname = h;
        // ASSERT: hostname is set.
        boolean runServer = true;
        // ASSERT: runServer is true.

        for (int i = 0; i < WHOISSERVER.length && runServer; i++) {
            try {
                System.out.println("Trying " + WHOISSERVER[i][0]);
                executeLookup(h, WHOISSERVER[i][0], Integer
                        .parseInt(WHOISSERVER[i][1]));
                runServer = false;
                // ASSERT: runServer is false.
            } catch (Exception e) {}
        }
        if (runServer) throw new java.net.UnknownHostException();
        // ASSERT: If runServer is still true, it means we never obtained
        // information about the domain.
    }

    /**
     * Performs WHOIS lookup and updates registrar, ns1, and ns2 for given
     * domain.
     * 
     * @param h
     *        Domain name to perform WHOIS lookup for.
     * @param serv
     *        WHOIS server to make request to.
     * @param port
     *        WHOIS port to make request on.
     * @throws Exception
     *         Throws UnknownHostException if WHOIS server contains no name
     *         server for domain (Assumed that the domain does not exist).
     */
    private void executeLookup(String h, String serv, int port)
            throws Exception {
        s = new Socket(serv, port);
        // ASSERT: s has been constucted to connect to the
        // whois server.
        s.setSoTimeout(WHOISTIMEOUT);
        // ASSERT: s socket timeout has been set.

        InputStream in = s.getInputStream();
        // ASSERT: in is set.
        OutputStream out = s.getOutputStream();
        // ASSERT: out is set.
        out.write((h + "\n").getBytes());
        // ASSERT: We have sent a whois request for hostname

        int tmp;
        // ASSERT: tmp is not set.
        String tmpString = "";
        // ASSERT: tmpString is not set.
        while ((tmp = in.read()) != -1)
            tmpString += (char) tmp;
        // ASSERT: tmpString is filled with the whois return.
        in.close();
        out.close();
        s.close();
        // ASSERT: socket, in & out buffers closed.
        // System.out.println (tmpString);
        tmpString = tmpString.toLowerCase();
        // ASSERT: tmpString is now all lowercase.

        if (tmpString.indexOf(NAMESERVER1STRING) >= 0) {
            setRegistrar(tmpString);
            // ASSERT: registrar is now set.
            setNameServers(tmpString);
            // ASSERT: ns1 & ns2 are now set.
        } else {
            throw new java.net.UnknownHostException();
        }
    }

    /**
     * Pulls registrar out of response from WHOIS server for domain lookup and
     * sets registrar to domain registrar or "" if none exist.
     * 
     * @param query
     *        WHOIS server response containing all the information about the
     *        domain.
     */
    private void setRegistrar(String query) {
        registrar = "";
        // ASSERT: registrar = "".
        int startIndex = query.indexOf(REGISTRARSTRING);

        // ASSERT: startIndex is now set to the index of where we can find
        // the REGISTRARSTRING.

        int indexOfLastSpace = -1;
        // ASSERT: indexOfLastSpace is -1.
        boolean foundChar = false;
        // ASSERT: foundChar is false.
        for (int i = startIndex + REGISTRARSTRING.length(); i < query.length()
                && i > 0 && query.charAt(i) != '\n'; i++) {
            if (!foundChar && query.charAt(i) != ' ') {
                registrar += query.charAt(i);
                foundChar = true;
                // ASSERT: foundChar is true.
            } else if (foundChar && query.charAt(i) == ' '
                    && indexOfLastSpace == -1) {
                indexOfLastSpace = i;
                registrar += query.charAt(i);
            } else if (foundChar && query.charAt(i) != ' ') {
                indexOfLastSpace = -1;
                registrar += query.charAt(i);
            }
        }
        if (indexOfLastSpace > -1) registrar = registrar.substring(0,
                indexOfLastSpace);
        // ASSERT: registrar is now set.
    }

    /**
     * Pulls name servers out of response from WHOIS server for domain lookup
     * and sets ns1 and ns2 to the domain name servers or "" if none exist.
     * 
     * @param query
     *        WHOIS server response containing all the information about the
     *        domain.
     */
    private void setNameServers(String query) {
        ns1 = "";
        // ASSERT: ns1 = "".
        ns2 = "";
        // ASSERT: ns2 = "".
        int startIndex = query.indexOf(NAMESERVER1STRING);
        // ASSERT: startIndex is now set to the index of where we can find
        // the NAMESERVER1STRING.

        for (int i = startIndex + NAMESERVER1STRING.length(); i < query
                .length()
                && i >= 0 && query.charAt(i) != '\n'; i++)
            ns1 += query.charAt(i);
        ns1 = ns1.replaceAll(" ", "");
        // ASSERT: ns1 is now set.

        // Find the second nameserver index
        if (NAMESERVER1STRING.equals(NAMESERVER2STRING)) startIndex = query
                .indexOf(NAMESERVER2STRING, startIndex
                        + NAMESERVER1STRING.length());
        else startIndex = query.indexOf(NAMESERVER2STRING);
        // ASSERT: startIndex is set to the beginning of the second nameserver
        // location.

        for (int i = startIndex + NAMESERVER2STRING.length(); i < query
                .length()
                && i >= 0 && query.charAt(i) != '\n'; i++)
            ns2 += query.charAt(i);
        ns2 = ns2.replaceAll(" ", "");
        // ASSERT: ns2 is now set.
    }

    /**
     * @return Hostname for current domain lookup.
     */
    public String getDomainname() {
        return hostname;
    }

    /**
     * @return Name server 1 for domain lookup, "" if domain does not exist.
     */
    public String getNS1() {
        return ns1;
    }

    /**
     * @return Name server 2 for domain lookup, "" if domain does not exist.
     */
    public String getNS2() {
        return ns2;
    }

    /**
     * @return Registrar for domain lookup, "" if domain does not exist.
     */
    public String getRegistrar() {
        return registrar;
    }
}